In the use of electronic watches, particularly, multifunction digital watches, it is necessary to have switches which enable the user of the watch to select the desired display function, or to set the information being displayed or to illuminate the display by activating lighting means. In the past, electronic watches have often employed one or more push-button switches to control the watch functions. These push-buttons most often employ a dynamic seal which is necessary to minimize or prevent moisture and other contaminants from entering the interior of the watch where delicate electronic components can be adversely affected.
Oftentimes, the push-button assembly includes a tube having an axially tapered bore for receiving a plunger. An O-ring is disposed around the plunger and a spring is used to provide tension on the push-button. Typical prior art push-buttons are shown in the U.S. Pat. No. 3,575,212 to Zellweger et.al. issued Sept. 11, 1973, U.S. Pat. No. 3,783,607 to Feurer issued Jan. 8, 1974 and U.S. Pat. No. 4,023,002 to Wuthrich issued May 10, 1977 as well as others. Switches of the typical push-button type are disadvantageous in that they are relatively high in cost, provide less than adequate sealing and detract from the overall appearance of the watch.
A push-button switch which sought to remedy these deficiencies is described in U.S. Pat. No. 4,031,348 issued June 21, 1977 to Noel Eberhardt. This switch comprises a single push-button member which includes a button and a shaft, the shaft being disposed within a bore and counterbore in a watchcase. A resilient, annular washer is disposed about the shaft of the push-button member within the counterbore and is shaped to sealingly engage the counterbore and push-button, functioning as both sealing means and return spring means for returning the push-button to the initial position after actuation.
Other types of switches for electronic watches have been devised by prior art workers. For example, a thin touch-type switch is disclosed in U.S. Pat. No. 4,241,246 to Lugaresi issued Dec. 23, 1980. Switch constructions for electronic calculator watches are disclosed in U.S. Pat. No. 4,072,004 to Tanaka et.al. issued Feb. 7, 1978 and in U.S. Pat. No. 4,184,321 to Tarusawa issued Jan. 22, 1980.
Switch constructions apparently for other uses are disclosed in the following patents. U.S. Pat. No. 3,999,287 to Lockard issued Dec. 28, 1976 discloses a rocker switch in which a pair of spaced contacts are embedded in a rocker arm and resiliently grip a diode therebetween that controls current direction of the completed circuit. U.S. Pat. No. 4,121,074 to Orcutt et.al. issued Oct. 17, 1978 involves a pressure responsive switch incorporating a rocker member for acting on a contact arm. U.S. Pat. No. 4,172,973 to Sano issued Oct. 30, 1976 discloses a seesaw switch with a light-emitting diode mounted upon a rockable member.